There are scam products - "laundry disks" or "laundry balls" - which take advantage of the fact that clothes still get pretty clean without using any powder. You use the thing (which costs $50+), don't use powder, and it something something magnets something something ions and wow your laundry gets clean!
Meanwhile, wool dryer balls are fantastic low-tech solution to static cling!
Most dryer balls also claim to reduce drying time, which is also untrue, although at least the claims are more grounded in physical possibility than the washing machine ones.
Wouldn't they help increase airflow around/between clothing?
In actual tests there's no difference in drying time found between using dryer balls and not using them.
Your wet sheets aren't going to dry if they're effectively tied in a knot. It's not some sort of mystery of physics.
If the toss a brick in the dryer, that will prevent your sheets from getting tied in a knot.
It'll instead prevent you from visiting the local laundromat ever again.
It is probably worth mentioning here that dryer sheets are mutagenic, and the toxins they leave in the clothes are absorbed through the skin.
My parents sent me off to college with a laundry disk, and I remember thinking I should visit my physics professor's office hours and ask how it worked. In retrospect I'm glad I didn't.
I have some spiked hard plastic balls which I think were intended for the dryer. They were about $5 for two from some chinese online retailer. I sometimes use them in the wash (with detergent) when I'm trying to clean particularly filthy items. I don't think they're magic but I assume they assist the cleaning through mechanical action.
Water (especially warm water) and mechanical action will remove a lot of simple stains already.